A cache is a fast memory that stores frequently accessed data so that future access requests for that data can be served quickly without repeatedly retrieving the same data from a comparatively slow backing store. A cache is a pool of entries where each entry has data and a tag. The tag identifies the corresponding data in the backing store. A page cache refers to a cache of disk-backed pages. When a page cache is full, a page eviction policy determines which page is removed to make room for a new page of data.
Use of the same reference numbers in different figures indicates similar or identical elements.